Cancer molecular diagnostics is becoming increasingly important with the accumulating knowledge of the molecular mechanisms underlying various types of cancers and the implications for diagnosis, treatment selection and prognosis.
Various molecular diagnostic tests like mutational analysis, methylation status of genomic DNA and gene expression analysis are currently being used to answer clinical questions. Differential gene expression analysis of cancer cells has so far primarily been done on cancer cells derived from surgically removed tumor tissue or from tissue obtained by biopsy. However, the ability to profile gene expression using a blood sample from a cancer patient rather than a tissue sample is desirable because a non-invasive approach such as this has wide ranging implications in terms of patient welfare, the ability to conduct longitudinal disease monitoring, and the ability to obtain expression profiles even when tissue cells are not easily accessible, e.g., in ovarian or brain cancer patients.
So far, gene expression profiling using a blood sample is confined to analyzing RNA extracted from Peripheral Blood Mononuclear Cells (PBMC) (Hakonarson et al., 2005) or Circulating Tumor Cells (CTC) (Cristofanilli and Mendelsohn, 2006). This invention discloses a novel method of profiling gene expressions and provides novel gene expression signatures associated with diseases by analyzing nucleic acids extracted from microvesicles from a bodily fluid, e.g., a blood sample.